1. Field of the Invention
The present invention relates generally to a device for detecting an automotive internal combustion engine having entered a idling mode of operation and more specifically to a idling detecting device which can be used in connection with the control of an automatic transmission lock-up clutch by way of example.
2. Description of the Prior Art
JP-A-62-62047 and JP-A-63-25165 disclose idling detection arrangements. In these types of idling detection devices, a switch is provided which is triggered when the engine assumes an idling mode of operation. This type of idling detection switch exhibits an ON/OFF type of operation and is triggered to switch from one state to another in response to the throttle valve assuming a fully closed position. When the switch is triggered by the throttle valve assuming a fully closed position, the lock-up clutch is controlled to assume a released state.
However, with this type of control, it is necessary to provide a separate throttle switch which thus increases the cost and complexity of the idle detection arrangement. That is to say, when an automatic transmission is used, it is necessary to provide the engine throttle valve with an additional switch which detects the same assuming a fully closed position.
Further, as this switch does not exhibit hysteresis and switches from one state to another (ON/OFF) in response to very small changes in throttle valve position, it sometimes occurs that vibration induces frequent switching between the ON and OFF states and deteriorates the lock-up clutch control to the point where the required smooth vehicle driving characteristics cannot be obtained.